This invention relates in general to an internal combustion engine equipped with a fuel injector for injecting the fuel into an intake passageway immediately upstream of a combustion chamber, and more particularly to an improvement in an air induction system of the engine to improve the character of air-fuel mixture to be supplied to the combustion chamber.
It is well known that the following advantages can be obtained by an internal combustion engine equipped with a fuel injectors for injecting fuel immediately upstream of combustion chambers: (1) In case of a multi-cylinder engine, fuel distribution to the cylinders is better, and uniform air-fuel mixtures can be supplied to the cylinders, improving the engine torque at low speed. (2) It is possible to cut the fuel supply during deceleration and to minimize the retardation of fuel supply, achieving the improvements in fuel economy etc.
However, a conventional fuel injector is arranged to inject fuel at a relatively low pressure such as 2 Kg/cm.sup.2 and accordingly atomization of the fuel is not good so that relatively large size fuel particles are injected from the injector. Such an arrangement is employed in a point of view of lowering production and operation costs. Further, since the distance from the fuel injector to the combustion chamber is short as compared with the case of an engine using a carburetor, homogenization of the air-fuel mixture is not sufficient and therefore the combustion chamber cannot be supplied with air-fuel mixture of better character.
Otherwise, it has also been proposed to promote the atomization of fuel by employing a so-called supersonic nozzle. However, this requires a separate pressurized air supply device, by which production and operation costs are unavoidably rendered considerably high.